The invention relates to a method for cleaning objects, such as workpieces just used for machining, which have been soiled, in particular, by oily or greasy impurities, with the aid of an aqueous cleaning fluid containing at least one washing agent. In this method, the objects are rinsed after treatment with the cleaning fluid with an aqueous rinsing fluid, in particular with water which is as pure as possible, and a distillate is recovered from cleaning and/or rinsing fluid following preliminary cleaning by distillation in a vaporizer and this distillate is fed back. In addition, the invention relates to a system for performing a method of this type, comprising at least one cleaning apparatus, one rinsing apparatus and one vaporizer, the cleaning apparatus being connected with the vaporizer via a cleaning fluid line and a precleaning apparatus for transferring cleaning fluid to the vaporizer and the vaporizer having a distillate line serving to feed back the distillate.
Washing agents are intended to be understood in the following as substances such as detergents and other washing agents in the narrow sense, but also organic solvents.
The Durr GmbH has already sold a system of the aforementioned type, in which the objects to be cleaned pass one after the other through two cleaning baths as well as a plurality of subsequent rinsing baths. Only completely desalinated water is supplied to the last two of a total of four rinsing baths while an overflow of the third rinsing bath is connected with the second rinsing bath and an overflow of the latter with the first rinsing bath. Moreover, an overflow of the first rinsing bath is connected with the second cleaning bath and an overflow of the latter with the first cleaning bath. An overflow from the first cleaning bath leads to an oil separator, and a rinsing fluid supply line branches off the overflow of the first rinsing bath. This supply line is provided with a valve and also leads to the oil separator. A discharge line leads from a clean fluid region of the oil separator to the vaporizer, from which a vapor and distillate line leads first of all to heat exchangers in the various cleaning and rinsing baths and then to a condensate collecting tank, from where the distillate is conveyed by a pump into the second rinsing bath. The baths are therefore heated with the vapor or distillate. Since the oil separator cannot completely prevent oily impurities passing into the vaporizer from the cleaning and rinsing baths, and since in this way washing agents are also supplied to the vaporizer, this known system has two disadvantages: Since there is no transition of detergents and the like into the vapor phase in the vaporizer, whereas this is the case for components of machining oils having a low boiling point and other substances which pass over into the vapor phase with the water vapor, the washing agents passing into the vaporizer are lost and the impurities contained in the distillate are a disturbance in the first two rinsing baths which are supplied from the condensate collecting tank.